drm/edid: convert drm_for_each_detailed_block() to edid iter

We have an iterator for this, use it. It does include the base block,
but its tag is 0 and will be skipped.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/a68718819a3dbfbdaaaddca7f73afa5ac6b33d07.1652097712.git.jani.nikula@intel.com